Corrosion inhibitors employing phosphate esters of cyclic amidines

ABSTRACT

WHERE $ IS CYCLIC AMIDINE-CONTAINING RADIAL FOR EXAMPLE IMIDAZOLINE AND TETRAHYDROPYRIMIDINE, X IS OXYGEN AND/OR SULFUR; R&#39;&#39; (WHICH MAY BE THE SAME OR DIFFERENT) IS HYDROGEN OR AN ALCOHOL MOIETY; N IS 1-3, AND M IS A NUMBER DETERMINED BY THE NUMBER OF HYDROXY GROUPS ON THE CYCLIC AMIDINE. THESE COMPOUNDS, AMOUNG OTHER USES, ARE EMPLOYED AS CORROSION INHIBITORS.   (A)N (-X-P(=X)-(X-R&#39;&#39;)3-N)M   ESTERS OF CYCLIC AMIDINES AND PHOSPHORIC ACIDS, INCLUDING OXYGEN, SULFUR AND OXYGEN AND SULFUR-CONTAINING PHOSPHORIC ACIDS, AS ILLUSTRATED BY ESTERS OF THE FORMULA

United States Patent 3,711,403 CORROSION INHIBITORS EMPLOYING PHOS-PHATE ESTERS OF CYCLIC AMIDINES Derek Redmore, Ballwin, Mo., assignor toPetrolite Corporation, Wilmington, Del.

No Drawing. Original application Sept. 11, 1967, Ser. No. 5 666,953.Divided and this application Jan. 18, 1971, Ser. No. 107,450

Int. Cl. C07d 49/34; C231? 11/16 US. Cl. 252-855 E 5 Claims ABSTRACT OFTHE DISCLOSURE Esters of cyclic amidines and phosphoric acids, includingoxygen, sulfur and oxygen and sulfur-containing phosphoric acids, asillustrated by esters of the formula where is a cyclicamidine-containing radical, for example imidazoline andtetrahydropyrimidine, X is oxygen and/or sulfur; R (which may be thesame or different) is hydrogen or an alcohol moiety; n is 1-3, and m isa number determined by the number of hydroxy groups on the cyclicamidine. These compounds, among other uses, are employed as corrosioninhibitors.

This application is a division of SN. 666,953, filed Sept. 11, 1967, nowUS. Pat. No. 3,585,210, patented on June 15, 1971.

This invention relates to esters of cyclic amidines and phosphoricacids. More particularly this invention relates to esters of the formulaF i 1 XP L (XR )a m where is a cyclic amidine-containing radical, forexample imidazoline and tetrahydropyrimidine; X is oxygen or sulfur; Ris hydrogen or an alcohol moiety; n=1 3; and m is a number determined bythe number of hydroxy groups on the cyclic amidine. (The Rs can all bethe same or different.) This invention also relates to uses for theseesters, including their uses as corrosion inhibitors. More specifically,in the above formula (A) contains either a imidazoline ortetrahydropyrimidine radical, for example, the following radicals3,711,403 Patented Jan. 16, 1973 i R=(COH).2 where R comprises, forexample, a saturated or unsaturated aliphatic radical, a cycloaliphaticradical, an aryl radical, an aralkyl radical, an alkaryl radical, nalkoxy alkyl radical, an aryloxy-alkyl radical, and the like; and A isan alkylene group; for erample, ethylene and propylene radicals, such asCH2CH2 -CH2CHzCHz CH2-CH- CH CH oHoH2- CH2 CH;

In general, the cyclic amidine, phosphate esters are prepared byreacting phosphorylating reagents such as phosphoric acid andthiophosphoric acids and derivatives of these such as anhydrides,partial anhydrides and halides, with the desired molar ratio of hydroxycontaining cyclic amidines for example of the formula More specifically,the corrosion inhibiting aspect of this invention relates to a methodfor inhibiting corrosion of ferrous metals by hydrocarbon fluidscontaining water and corrosive materials such as H 8, CO inorganicacids, or ganic acids, etc., combinations of these materials with eachother, combinations of each of said corrosive materials with oxygen, andcombinations of said materials with each other and oxygen, whichcomprises adding to said fluids at least five parts per million of theabove cyclic amidine esters, said compounds being sufiiciently solublein the hydrocarbon fluid to inhibit corrosion.

THE HYDROXY CYCLIC AMIDINE The expression cyclic amidines is employed inits usual sense to indicate ring compounds in which there are usuallypresent either five members or six members, and having two nitrogenatoms separated by a single carbon atom supplemented by either twoadditional carbon atoms or three additional carbon atoms completing thering. All the carbon atoms may be substituted. In the present instance,the nitrogen atom of the ring involving two monovalent linkages (i.e. atthe one-position) is substituted with a hydroxy-containing group forexample as represented by A0 H /D where A is alkylene, n is a number forexample 1-10 or higher, but preferably 1-3.

The hydroxy cyclic amidine is thus represented by the formula:

These cyclic amidines are further characterized as being substitutedimidazolines and tetrahydropyrimidines in which the two-position carbonof the ring is generally bonded to a hydrocarbon radical or comparableradical derived from an acid, such as a low molal fatty acid, a highmolal fatty acid, or comparable acids, polycarboxy acids, and the like.

For details of the preparation of imidazolines substituted in the2-position from amines, see the following U.S. patents, U.S. No.1,999,989, dated Apr. 30, 1935, Max Bockmuhl et al.; U.S. No. 2,155,877,dated Apr. 25, 1939, Edmund Waldmann et al.; and U.S. No. 2,155,878,dated Apr. 25, 1939, Edmund Waldmann et al. Also see Chem. Rev. 32, 47(1943), and Chem. Rev. 54, 593 (1954).

Equally suitable for use in preparing compounds of my invention and forthe preparation of tetrahydropyrimidines substituted in the 2-positionare the polyamines containing at least one primary amino group and atleast one secondary amino group, separated from the first primary aminogroup by three carbon atoms instead of being separated by only 2 carbonsas with imidazolines. This reaction, as in the case of the imidazolines,is generally carried out by heating the reactants to a temperature atwhich 2 mols of water are evolved and ring closure is effected. Fordetails of the preparation of tetrahydropyrimidines, see German Pat. No.700,371, dated Dec. 18, 1940, to Edmund Waldmann and August Chwala;German Pat. No. 701,322 dated Jan. 14, 1941, to Karl Kiescher, ErnstUrech and Willi Klarer, and U.S. Pat. No. 2,194,419, dated Mar. 19,1940, to August Chwala.

Substituted imidazolines and tetrahydropyrimidines are obtained from avariet of acids beginning with the onecarbon acid (formic) through andincluding higher fatty acids or the equivalent having as many as 32carbon atoms. Modified fatty acids also can be employed as, for example,phenyl stearic acid or the like. Cyclic acids may be employed, includingnaphthenic acids. A variety of other acids including benzoic acid,substituted benzoic acid, salicylic acid, and the like, have beenemployed to furnish the residue from the acid RCOOH in which the C ofthe residue R35.

is part of the ring. The fatty acids employed, for example,

may be saturated or unsaturated. Branched long cham fatty acids may beemployed. See J. Am. Chem. Soc. 74,

2523 (1952). This applies also to the lower molecular weight acids aswell. I

Among sources of such acids may be mentioned straight chain and branchedchain, saturated and unsaturated, aliphatic, cycloaliphatic, aromatic,hydroaromatic, aralkyl acids, etc.

Examples of saturated aliphatic monocarboxyhc acids, comprise: acetic,propionic, hutyric, valeric, caproic, heptanoic, caprylic, nonanoic,capric, undecanolc, laurlc, tndecanoic, myriatic, pentadecanoic,palmitic, heptad ecanoic, stearic, nonadecanoic, eicosanoic,heneicosanoic, docosanoic, tricosanoic, tetracosanoic, pentacosanoi c,cerotic, heptaconsanoic, montanic, nonacosanoic, meliss1c and the like.

Examples of ethylenic unsaturated aliphatic acids comprise: angelic,tiglic, the pentenoic acids, the hexenoic acids, for example,hydrosorbic acid, the heptenolc ac ds, the octenoic acids, the nonenoicacids, the decenoic acids, for example, obtusilic acid, the undecenoicacids, the dodecenoic acids, for example, lauroleic, linderic, etc., thetridecenoic acids, the tetradecenoic acids, for example, myristoleicacid, the pentadecenoic acids, the hexadecenoic acids, for example,palmitoleic acid, the heptadecenoic acids, the octodecenoic acids, forexample, petrosilenic acid, oleic acid, elardic acid, the nonadecenoicacids, for example, the eicosenoic acids, the docosenoic acids, forexample, erucic acid, brassidic acid, cetoleic acid, the tetracosenicacids, and the like.

Examples of dienoic acids, comprise the pentadienoic acids, thehexadienoic acids, for example, sorbic acid, the octadienoic acids, forexample, linoleic, and the like.

Examples of the trienoic acids comprise the octadecatrienoic acids, forexample, linolenic acid, eleostearic acid, pseudo-eleostearic acid, andthe like.

Examples of the cyclic aliphatic carboxylic acids comprise those foundin petroleum called naphthenic acids, hydrocarbic and chaulmoogricacids, cyclopentane carboxylic acids, cyclohexanecarboxylic acid,campholic acid, fencholic acids, and the like.

Examples of aromatic monocarboxylic acids comprise benzoic acid,substituted benzoic acids, for example, the toluic acids, the xyleneicacids, alkoxy benzoic acid, phenyl benzoic acid, naphthalene carboxylicacid, and the like.

Mixed higher fatty acids derived from animal or vegetable sources, forexample, lard, coconut oil, rapeseed oil, sesame oil, palm kernel oil,palm oil, olive oil, corn oil, cottonseed oil, sardine oil, tallow,soyabean oil, peanut oil, castor oil, seal oils, whale oil, shark oil,and other fish oils, teaseed oil, partially or completely hydrogenatedanimal and vegetable oils are advantageously employed. Fatty and similaracids include those derived from various waxes, such as beeswax,spermaceti, montan wax, Japan Wax, coccerin and carnauba wax. Such acidsinclude carnauhic acid, cerotic acid, lacceric acid, montanic acid,psyllastearic acid, etc. One may also employ higher molecular weightcarboxylic acids derived by oxidation and other methods, such as fromparafiin wax, petroleum and similar hydrocarbons; resinic andhydroaromatic acids, such as hexahydrobenzoic acid, hydrogenatednaphthoic, hydrogenated carboxy diphcnyl, naphthenic, and abietic acid,aralkyl and aromatic acids, such as Twitchell fatty acids, naphtholicacid, carboxydiphenyl pyridine carboxylic acid, blown oils, blown oilfatty acids and the like.

Other suitable acids include phenylstearic acid, etc.

Examples of the polycarboxylic acids comprise those of the aliphaticseries, for example, oxalic, malonic, succinic, glutaric, adipic,pimelic, suberic, azelaic, sebacic, nonanedicarboxylic acid,decanedicarboxylic acids, undecanedicarboxylic acids, and the like.

Examples of aromatic polycarboxylic acids comprise isophthalic acids,terephthalic acids, substituted derivatives thereof (e.g. alkyl, chloroalkoxy, etc. derivatives), biphenyldicarboxylic acid, diphenyletherdicarboxylic acids, diphenylsulfone dicarboxylic acids and the like.

Other polycarboxylic acids comprise the dimeric, trimer1c and polymericacids, for example, diricinoleic acid, triricinoleic acid,polyricinoleic acid, and the like. Other polycarboxylic acids comprisethose containing ether groups, for example, diglycollic acid. Mixturesof the above acids can be advantageously employed.

In addition, acid precursors such as esters, acid chlor1des, glycerides,etc. can be employed in place of the free acid.

. llydroxy substituted imidazolines and tetrahydropyrimidmes can beobtained in the manner described above from a wide variety of polyaminescontaining hydroxy groups. Thus, where one starts with a polyamine, forexample, a diamine of the following formula:

where R has for example 2 or 3 carbons in its main chain one obtains thecompounds of this invention. In addition, one can start with ethylenediamine or with 1,2-propylene diamine, 1,3-propylenediamine or otherpolyamines and then react the cyclic amidine so obtained with alkyleneoxides so as to produce a terminal hydroxy group since the nitrogenbonded hydrogen on the 1-position on the ring reacts with alkyleneoxides. Polyoxyalkylated cyclic amidines can be prepared by reacting ahydroxyalkylcyclic amidine with an alkylene oxide.

Alkylene oxides comprise those of the general formula where R is analkyl group. Among the alkylene oxides that may be employed areethylene, propylene, butylene,

7 THE PI-IOSPHORIC ACID MOIETY The desired products are obtained byreacting a hydroxy-containing amidine with a phosphorylating reagentwhich is a derivative of phosphoric acid. The reaction products can bedescribed by the formula X @-Xll -XR where X =O or S is ahydroxy-containing cyclic amidine, R and R, which can be the s-ame ordifferent, are (A), H, alkyl (e.g. methyl, ethyl, propyl, hexyl, 2-ethylhexyl, lauryl, etc.), cycloalkyl (e.g. cyclopentyl, cyclohexyl, etc.),aryl (phenyl, tolyl, etc.), or heterocyclic (e.g. furfuryl, etc.).

All of the Xs may be oxygen or all sulfur or some of the Xs may beoxygen and the others sulfur.

The simplest phosphorylating reagent which can be used isorthophosphoric acid but this requires vigorous conditions to bringabout reaction. The products from this reagent are mainly monoesters,

Reagents which are generally preferred as phosphorylating reagents areanhydrides, partial anhydrides, and acid halidesof phosphoric acid.These reagents require much milder conditions than orthophosphoric acidsince they are highly reactive and furthermore give much better yieldsof the required products. The exact reagent of choice will depend on theindividual hydroxy-containing imidazoline to be reacted and on thestructure of the product required. For example, phosphorus pentoxide isa powerful phosphorylating reagent which on reaction with ahydroxy-containing imidazoline yields a mixture of monoand di-esters,

The ratio of monoto di-ester depends on the ratio of hydroxy compound tophosphorus pentoxide reacted. Part of the hydroxy containing imidazolinecan be replaced by a simple aliphatic alcohol such as ethanol in whichcase the product will contain a more complex mixture, e.g.

etc.

Phosphorus pentasulfide is similarly a powerful phosphorylating reagentwhich with hydroxy compounds gives similar products to those fromphosphorus pentoxide in which some or all of the oxygens are replaced bysulfur.

Polyphosphoric acid is intermediate in behavior between orthophosphoricacid and phosphorus pentoxide since it is a partial anhydride ofphosphoric acid. This reagent is particularly useful in preparingmonoesters of phosphoric acid. For example, on reacting equimolara-mounts of polyphosphoric and a hydroxy containing cyclic amidine themain product is a phosphate monoester,

Another very important group of phosphorylating reagents which are usedto prepare the products of this invention are acid halides of phosphoricacid. Among these are phosphoryl halides, POX (X=CI, Br),phosphorochloridates,

where R is alkyl, cycloalkyl, aryl, heterocyclic),phosphorodichloridates,

ll ROPClz (where R is as defined above). For example, aphosphorochloridate can be reacted with a hydroxy-containing amidine togive a triester as follows:

R is as defined above.

The hydrogen chloride is taken up by the cyclic amidine ring in thereaction. However, in some cases it may be desirable to add a base toremove the acid, for example a tertiary amine may be used such aspyridine, quinoline, etc, or an alkali metal oxide or carbonate such asbarium carbonate, calcium carbonate or calcium oxide,-etc.

Other methods for phosphorylation are known and can be found describedin Structure and Mechanism in Organo-Phosphorus Chemistry, pp. 250-280by R. F. Hudson, Academic Press 1965, -F. Cramer, in New Methods ofPreparative Organic Chemistry, vol. HI, pp. 319-356, Ed. W. Foerst,Academic Press 1964.

The following examples are presented for purposes of illustration andnot of limitation.

EXAMPLE 1 Oleic acid (0.5 mole) was heated with hydroxyethyl ethylenediamine (0.5 mole) in xylene using a Dean & Stark tube to collect thewater produced. When one mole of water (18 ml.) had been collected thexylene was removed by distillation to yield 1-3-hydroxyethyl-2-heptadecenyl-Z-imidazoline. To this hydroxyethylimidazoline (50 g.; 0.143 mole) was added polyphosphoric acid (115%ortho equivalent) (27.2 g.; 0.16 mole) with vigorous stirring. Thereaction involved considerable heat. On completion of the addition themixture was heated at for one hour to yield a benzene-soluble product.The product is mainly the phosphate ester of the hydroxyethylimidazoline. The formula can be represented as CH2CH:4 N /NCHzCHzO-l OHEXAMPLE 2 CH2GI-I:

( Hzh or a (I311 HM or 1 EXAMPLE 3 Preparation of a hydroxyethylimidazoline. Crofatol P (1 equivalent) was heated with hydroxyethylethylene diamine (1 mole) at -185 for four hours under reduced pressure(approximately 100 mm.) in a reaction flask fitted with a condenser fordistillation. During the period of reaction, water (2 moles) distilledoff and was collected.

The product was mainly a l-B-hydroxyethyl imidazoline. Crofatol P is acommercial fatty acid mixture comprised of C acids including linoleic,oleic and stearic acids.

EXAMPLE 4 This product was prepared in the same manner as Example 4except that the mole ratio of hydroxyethyl imidazoline to polyphosphoricacid was 1.34:1 instead of 1:1. The product is represented by theformulae:

|CHz-CH3 (I) C3H2CH2 (II) N N-OHZCHZO -(H), N N-CHzCHzO P-OH C C it it 2EXAMPLE 6 The hydroxyethyl imidazoline of Example 3 (95 g.; 0.25 mole)was dissolved in kerosene (120 ml.) and to the resulting solution wasadded diethyl phosphorochloridate (43.1 g.; 0.25 mole) during 15 mins.The reaction was mildly exothermic giving a reaction temperature of 60.Following the addition the reaction was completed by heating at 7585 fortwo hours. The product is a triester of phosphoric acid of the followingformula:

021350 0 OHr-CH:

P-OCH2CH$N N -HOI (EH50 o R EXAMPLE 7 To the hydroxyethyl imidazoline ofExample 3 151 g.; 0.4 mole) in kerosene (120 ml.) was added ethylphosph'orodichloridate (32.6 g.; 0.2 mole) during 15 minutes. Thereaction was exothermic giving a temperature of 70 at the end of theaddition. The reaction was completed by heating at 7075 for 2% hourswith stirring. The product was a triester of phosphoric acid which isrepresented as follows:

EXAMPLE 8 To the hydroxyethyl imidazoline of Example 3 (94.8 g.; 0.25mole) dissolved in kerosene (225 mls.) was added bis (Z-ethyl hexyl)phosphorochloridate (85.4 g.; 0.25 mole) dropwise during ten minutes.The addition was only very mildly exothermic and the reaction wasbrought to com- CzHsO -HO1 1 0 pletion by heating at 70-85 for twohours. The product was a triester of phosphoric acid of the followingformula:

CaHuO O CHz CH2 CgHnO l EXAMPLE 9 Phosphorus pentoxide (17.8 g.; 0.13mole) was added to a solution of the hydroxyethyl imidazoline of Example3 (94.5 g.; 0.25 mole) in xylene (180 ml.). The mixture was heated withstirring at (reflux) for four hours at which time all the phosphoruspentoxide had reacted. The product is a mixture of phosphoric acidesters of the following formulae:

0 (1) ROP(OH)2 (2) (ROhl OH (3) (ROhP EXAMPLE 10 This product is formedin a :reaction identical with Example 9 except that ratio of phosphoruspentoxide to hydroxyethyl imidazoline is 1:3 instead of 1:2. The productis a mixture of phosphate esters of the following formulae:

EXAMPLE r1 Phosphorus pentasulfide (22.2 g.; 0.1 mole) was added to asolution of the hydroxyethyl imidazoline of Example 3 ('113 g. 0.3 mole)in xylene (155 ml.). The mixture was heated at 140 for two hours atwhich time the solid phosphorus pentasulfide had completely dissolved.Heating was continued for a further 2 /2 hours to complete the reaction.The product of this reaction is a mixture of thiophosph'ate esters whichcan be represented by the formulae:

5 s I I (R on SHR OP(SH)2 where R:

CH2-CH2 EXAMPLE 12 To a solution of ethylene diamine g.; 2.5 moles) inethanol (200 ml.) warmed to 40 was added l-tetradecyloxy2,3-oxidopropane (135 g.; 0.5 mole) dropwise during 75 minutes. Themixture was heated at 7080- for two hours to complete the reaction. Theproduct was obtained by evaporation of the solvent and excess ethylenediamine under vacuum. The product is mainly the substituted ethylenediamine with the following structure:

NH; O H2 CHZNH-CH2 CH- CHr-O C H19 l l\\ /NCH2 C I t R=C11 EXAMPLE 13The hydroxy imidazoline of Example 12 (172 g.; 0.3 mole) was dissolvedin xylene (210 mls.) and treated with phosphorus pentoxide (14.2 g.; 0.1mole). The mixture was heated under reflux with exclusion of moisturefor 3 /2 hours at which time the reaction was complete. The productconsists of a mixture of phosphate esters derived from the imidazolinewhich can be represented as follows:

Roi (oHz(0'0)r1 oH R'0)3i where R O O H29 H: CH2CH2 JH-CHTN 1 1 R isderived from Crofatol P.

EXAMPLE 14 EXAMPLE 15 Following the procedure of Example 12 ethylenediamine was reacted with a commercial epoxide, Nedox 1114 (a mixture ofC to C 1,2-epoxides) (average M.W. 189), to produce the substitutedhydroxyethyl ethylene diamine of the following formula This hydroxyethylethylene diamine was then reacted with an equimolar amount of Crofatol Pto produce a hydroxyethyl imidazoline of the following formula:

R=C9 to C12 mixture.

EXAMPLE 16 The procedure of Example 15 was followed except that Nedox1114 was replaced by an equimolar amount of Nedox 1518 which is amixture of C to C 1,2-epoxides 12 of average molecular weight 245. Theimidazoline resulting from this sequence of reactions has the followingformula:

R=C to C mixture.

EXAMPLE 17 The hydroxy-containing imidazoline of Example 15 (0.15 mole)was heated with phosphorus pentoxide (0.05 mole) in xylene ml.)following the method of Example 9. The product is similarly a mixture ofphosphate esters.

EXAMPLE 18 This product is formed in a manner similar to that of Example17 except that the imidazoline of Example 15 is replaced by theimidazoline of Example 16.

EXAMPLE 19 In the manner of Example 8 the hydroxy-containing imidazolineof Example 15 (0.1 mole) was reacted with bis(2-ethyl hexyl)phosphorochloridate (0.1 mole) in kerosene to yield a triester ofphosphoric acid.

EXAMPLE 20 In this example the imidazoline of Example 15 is replaced bythat of Example 16 and the method of Example 19 is followed to give aphosphate triester.

USE AS CORROSION INHIBITOR More specifically, this phase of theinvention relates to the inhibition of corrosion in the petroleumindustry with specific reference to producing wells, pipe lines,refineries, tank storage, etc.

The use of a corrosion inhibiting agent in the oil industry and otherindustries, and particularly for the protection of ferrous metals, iswell known. For example, see US. Pats. Nos. 2,736,658, dated Feb. 28,1954, to Pfohl et al., and 2,756,211, dated July 24, 1956, to Jones, and2,727,003, dated Dec. 13, 1955, to Hughes.

More specifically then, and particularly from the standpoint of oilproduction, this aspect of the invention relates to inhibiting corrosioncaused by hydrogen sulfide, carbon dioxide, inorganic and organic acids,combinations of each with oxygen, and with each other and oxygen. Moreparticularly, it relates to treating wells to mitigate metal corrosionand associated difficulties.

It should also be pointed out that the corrosiveness of oil well brineswill vary from well to well, and the proportion of corrosion inhibitingagent added to the well fluids should also be varied from well to well.Thus, in some wells it is possible to effectively control corrosion bythe addition of as little as 5 p.p.m. of my new compositions to the wellfluids, whereas in other wells, it is necessary to add 200 p.p.m. ormore.

In using my improved compositions for protecting oil well tubing, casingand other equipment which comes in contact with the corrosive oil-brineproduction, I find that excellent results may be obtained by injectingan appropriate quantity of a selected composition into a producing wellso that it mingles with the oil brine mixture and comes into contactwith the casing, tubing, pumps and other producing equipment. I can, forexample, introduce the inhibiting composition into the top of thecasing, thus causing it to flow down into the well and thence backthrough the tubing, etc. In general, I have found that this proceduresuflices to inhibit corrosion throughout the entire system ofproduction, and collection, even including field tankage.

In case serious emulsion or gel problems are encountered, demulsificrsare advantageously added. This is important not only to avoid thetroublesome emulsionsand gels themselves, but also to improve corrosioninhibition. The explanation of less effective corrosion inhibition inthe presence of emulsions apparently is that the inhibitor is somewhatsurface-active. That is, it is concentrated at interfacial surfaces.Since this surface is great in an emulsion, most of the inhibitor willbe concentrated in these interfaces and little will remain in the bodyof the oil for deposition on the metal surfaces. In many wells,oil-inwater type emulsions often occur naturally. In such wells theinhibitors herein described tending to form water-inoil emulsions, oftendecrease the emulsion problem naturally present. Thus, in addition tobeing effective corrosion inhibitors, the herein described products tendto eliminate emulsion problems which sometimes appear when some of th'epresent day inhibitors are used in oil wells or refinery processing.

The method of carrying out my process is relatively simple in principle.The corrosion preventive reagent is dissolved in the liquid corrosivemedium in small amounts and is thus kept in contact with the metalsurface to be protected. Alternatively, the corrosion inhibitor may beapplied first to the metal surface, either as is, or as a solution insome carrier liquid or paste. Continuous application, as in thecorrosive solution, is the preferred method, however.

The present process finds particular utility in the protection of metalequipment of oil and gas wells, especially those containing or producingan acidic constituent such as H S, CO inorganic and organic acids, andthe like. For the protection of such wells, the reagent, eitherundiluted or dissolved in a suitable solvent, is fed down the annulus ofthe well between the casing and producing tubing where it becomescommingled with the fluid in the well and is pumped or flowed from thewell with these fluids, thus contacting the inner wall of the casing,the outer and inner wall of tubing, and the inner surface of allwell-head fittings, connections and flow lines handling the corrosivefluid.

Where the inhibitor composition is a liquid, it is conventionally fedinto the well annulus of a motor driven chemical injector pump, or itmay be dumped periodically (e.g. once every day or two) into the annulusby means of a so-ca1led boll weevil device or similar arrangement. Wherethe inhibitor is a solid, it is dropped into the well as a solid lump orstick, blown in as a powder with gas, or washed in with a small streamof the well fluids or other liquid. Where there is gas pressure on thecasing, it is necessary, of course, to employ any of these treatingmethods through a pressure equalizing chamber equipped to allowintroduction of reagent into the chamber, equalization of pressurebetween chamber and casing, and travel of reagent from chamber to wellcasing.

Occasionally, oil and gas wells are completed in such a manner thatthere is no opening between the annulus and the bottom of the tubing orpump. This results, for example, when the tubing is surrounded at somepoint by a packing held by the casing or earth formation below thecasing. In such wells the reagent may be introduced into the tubingthrough a pressure equalizing vessel, after stopping the flow of fluids.After being so treated, the Well should be left closed in for a periodof time sufiicient to permit the reagent to drop to the bottom of thewell.

For injection into the well annulus, the corrosion inhibitor is usuallyemployed as a solution in a suitable solvent, such as mineral oil,methylethyl ketone, xylene, kerosene, or even water. The selection ofsolvent will depend much upon the exact reagent being used and itssolubility characteristics. It is also generally desirable to employ asolvent which will yield a solution of low freezing point, so as toobviate the necessity of heating the solution and injection equipmentduring winter use.

For treating wells with packed-off tubing, the use of solid sticks orplugs of inhibitor is especially convenient. These are prepared byblending the inhibitor with a min eral wax, asphalt or resin in aproportion suflicient to give a moderately hard and high-melting solidwhich can be handled and fed into the well conveniently.

The amount of corrosion preventive agent required in my process varieswith the corrosiveness of the system, but where a continuous orsemicontinuous treating procedure is carried out as described above, theaddition of reagent in the proportion of from 5 parts per million to1000 parts per million or more parts of corrosive fluid will generallyprovide protection.

These corrosion inhibitors can be used in combination with otherwell-known corrosion inhibitors, for example, the cyclic amidinestructures, the amido cyclic amidine structures, and the amino cyclicamidine structures, as disclosed in the Blair and Gross Reissue Pat. No.23,227.

As pointed out previously, the addition of corrosion inhibitors,particularly in the form of a solution by means of a metering pump orthe like, is common practice. The particular corrosion inhibitors hereindescribed are applied in the same manner as other corrosion inhibitorsintended for use for the same purpose. As to the use of the corrosioninhibitor, a solution of it can be prepared in a suitable solvent suchas mineral oil, methyl ethyl ketone, Xylene, kerosene, high boilingaromatic solvent, or even water.

The following examples are presented to illustrate the superiority ofthe instant compounds as corrosion inhibitors.

CORROSION TESTS The test procedure includes measurement of the corrosiveaction of the fluids inhibited by the compositions herein described uponsand-blasted SAEFlOZO steel coupons under conditions approximating thosefound in an actual producing well, and the comparison thereof withresults obtained by subjecting identical test coupons to the corrosiveaction of the identical fluids containing no inhibitor.

In the present tests clean pint bottles are charged with 300 ml. of asynthetic brine, which contains 42 g. of sodium chloride, 1.4 g. calciumchloride, 1 g. of sodium sulfate, and 17 g. of magnesium chloride perliter, and 140 ml. of kerosene both saturated with hydrogen sulfide anda predetermined amount of inhibitor is then added. In all cases theinhibitor concentration is based on the total volume of fluid. Bottlecaps holding three coupons are then placed tightly on the bottles. Thebottles are then placed on a wheel contained in an oven and rotated for4 hours at 95" F. Corrosion rates are then measured using the threecoupons in each bottle as electrodes in conjunction with an instrumentfor measurement of instantaneous corrosion rates. Percent protection iscalculated from R1 Xl00% where R is corrosion rate of uninhibited fluidsR is corrosion rate of inhibited fluids.

Film life is then determined by replacing fluids in each bottle with 300ml. brine and ml. kerosene saturated with hydrogen sulfide as before butno inhibitor. Heating and rotation is continued in the oven at 90-95 F.and corrosion rates measured at various times. The inhibitor film on thecoupons gradually is lost in this stage of the test and is followed byan increase in corrosion rate. Once the protection falls below 85% thefilm is considered unsatisfactory and this marks the end of film life.It can be appreciated that the longer the film life the more useful theinhibitor. The compositions of this invention give excellent protectionin presence of inhibitor and particularly give long film life whensubjected to the above test. The data contained in the following tableclearly demonstrate the superior quality of the phosphate esters of thecyclic amidines compared with the related unphosphorylated cyclicamidines.

TABLE V Concen- Percent Film tration, proteclife,

p.p.m. tion hrs. Comments 100 98 4 Hydroxy containing cyclic ami ne. 7590 5 Phosphorus derivatives of Example 3. 75 100 Do. 75 99 D0. 75 99 15Do. 75 98 15 Do. 100 99 5 Do.

60 99 4 Hydroxy-containing cyclic am ine. 60 99 15 Phosphorus derivativeof Example 15 60 94 4 Do.

*This indicates that the compound prepared in the example indicated wasemployed as the corrosion inhibitor.

OTHER USES These products are effective not only as corrosion inhibitorsbut can be used for a number of other purposes. For instance, they areuseful as asphalt additives to increase the adhesiveness of the asphaltto the mineral aggregates. Where they contain oxyalkylation susceptiblegroups, they can be subjected to extensive oxyalkylation by means ofethylene oxide, propylene oxide, butylene oxide, octylene oxide, etc.These are oxyalkylated and still have oil solubility as, for example, bythe addition of propylene oxide or butylene oxide, or are oxyalkylatedto produce water solubility as, for example, by means of ethylene oxideor glycide. They are also oxyalkylated by combinations of propyleneoxide and ethylene oxide so that both water solubility and oilsolubility remain. Such products are useful for a variety of purposesand particularly for those where nonionic surfactants or sequesteredcationic surfactants are indicated.

In addition, the present compounds, or the oxyalkylated derivativesthereof and salts of either have the following applications:

As demulsifiers and desalters for water-in-oil emulsions; asdemulsifiers for oil-in-water emulsions; as fuel oil additives forgasoline, diesel fuel, jet fuel, and the like; as lubricating oiladditives; as scale preventatives; as chelating agents or to formchelates which are themselves useful, for example, as anti-oxidants,fungicides etc.; as flotation agents, for example, as flotationcollection agents; as additives for compositions useful in acidizingcalcareous strata of oil wells; as additives for treating Water used inthe secondary recovery of oil and in disposal wells; as additives usedin treating oil-Well strata in primary oil recovery to enhance the flowof oil; as emulsifiers for both oil-in-water and water-in-oil emulsions;as additives for slushing oils; as additives for cutting oils; asadditives for oil to prevent emulsification during transport; asadditives for drilling muds; as agents useful in removing mud sheathsfrom newly drilled wells; as dehazing or fog-inhibiting agents forfuels; as additives for preparing sand or mineral slurries useful intreating oil wells to enhance the recovery of oil; as agents forproducing polymeric emulsions useful in preparing water-vaporimpermeable paper board; as agents in paraffin solvents; as agents inpreparing thickened silica aerogel lubricants; as gasoline anti-oxidantadditives; as deicing agents for fuels; as antiseptic, preservative,bactericidal, bacteriostatic, germicidal, fungicidal agents; as agentsfor the textile industry, for example, as mercerizing assistants, aswetting agents, as rewetting agents, as dispersing agents, asdetergents, as penetrating agents, as softening agents, as dyeingassistants, as anti-static agents, and the like; as additives for rubberlatices; as an entraining agent for concrete and cements; as anti-staticagents for rugs, floors, upholstery, plastic and wax polishes, textiles,etc.; as detergents useful in metal cleaners, in floor oils, in drycleaning, in general cleaning, and the like; as agents useful in leatherprocesses such as in flat liquoring, pickling, acid degreasing, dyefixing, and the like; as agents in metal pickling, as additives inpaints for improved adhesion of primers, in preventing water-spotting inlacquer; as anti-skinners for pigment flushing, grinding and dispersing;as antifeathering agents in ink; as agents in the preparation of woodpulp and pulp slurries; as emulsifiers for insecticidal compositions andagricultural sprays such as DDT, 24-D (Toxaphene), chlordan, nicotinesulfate, hexachlorocyclohexane, and the like; as agents useful inbuilding materials, for example, in the water repellent treatment ofplaster, concrete, cement, roofing materials, floor sealers; as additivein bonding agents for various insulating building materials; and thelike.

I claim:

1. A process of inhibiting corrosion of ferrous metals and alloys inproducing Wells, pipe lines, refineries, storage tanks and equipmentrelated thereto comprising contacting said metals and alloys with cyclicamidine esters of phosphoric acids, or mixtures thereof, or hydrohalidesalts of said cyclic amidine esters of phosphoric acids, or mixturesthereof, said cyclic amidine esters of phosphoric acids being of theformula XXY wherein X is oxygen,

Y is hydrogen, alkyl of 1 to 12 carbon atoms, cyclopentyl, cyclohexyl,phenyl, tolyl, furfuryl or a cyclic amidine of the formula R is a memberselected from the group consisting of a mixture Of CgH19, C10H21, C11H23and C H and a mixture of ra z'z 14 29 15 31 and C16H33,

with the proviso that at least one of the Ys is one of the foregoingcyclic amidine members.

1 7 2. The process of claim 1 wherein Y is 4. The process of claim 3wherein Y is 5. The process of claim 4 wherein said metals and alloysare contacted with hydrohalicle salts of the formula R being a mixtureof OH (CH (CH CH=CH) (CH 10 and CH3(CH2)16- References Cited UNITEDSTATES PATENTS 2,927,080 3/1960 Westlund et a1. 252-389 X 8-94.1 P, 125;106-14, 281 N; 252-344, 389, 400, 542; 260-251 P, 309.6; 424-200

